Photochemical cross-linkable polymers, methods of making photochemical cross-linkable polymers, methods of using photochemical cross-linkable polymers, and methods of making articles containing photochemical cross-linkable polymers

ABSTRACT

Structures having a polymer composition covalently bonded to the surface of the structure, methods of attaching the polymer to the surface of the structure, methods of decreasing the amount of microorganisms formed on a structure, and the like, are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of co-pending U.S. application Ser. No.13/643,411 filed Oct. 25, 2012, which is the 35 U.S.C. §371 nationalstage of PCT application having serial number PCT/US2011/034268, filedon Apr. 28, 2011. The PCT application claims priority to and benefit ofU.S. Provisional Application No. 61/328,879 filed on Apr. 28, 2010 andU.S. Provisional Application No. 61/370,919, filed on Aug. 5, 2010, eachof which are incorporated by reference in their entireties.

BACKGROUND

Microbial infection is one of the most serious concerns for manycommercial applications such as textiles, food packaging and storage,shoe industry, water purification, medical devices, and dental surgeryequipment. Recently, antimicrobial agents have gained significantinterest from both an academic and industrial point of view because oftheir potential to provide safety benefits to a diverse range ofmaterials. Thus, there is a need to discover antimicrobial agents thataddress current needs.

SUMMARY

Polymer compositions, methods of making polymer compositions, structureshaving the polymer composition covalently bonded to the surface of thestructure, methods of attaching the polymer to the surface of thestructure, methods of decreasing the amount of microorganisms formed ona structure, and the like, are disclosed.

An exemplar embodiment of a polymer, among others, includes a linear orbranched polyethylenimine polymer that has been quaternized with ahydrophobic side chain moiety and a photo cross-linkable moiety.

An exemplar embodiment of a method of disposing a polymer on a surface,among others, includes: providing a polymer of the present disclosure;disposing the polymer on a structure having a surface having C—H groups;and exposing the polymer to a UV light, wherein the interaction of thepolymer with the UV light causes the polymer to covalently bond with thesurface

An exemplar embodiment of a structure, among others, includes: a surfacehaving a polymer of the present disclosure covalently attached to thesurface, wherein the structure has an antimicrobial characteristic.

An exemplar embodiment of a materila, among others, includes: a vinylmoiety and a photo cross-linkable moiety.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of this disclosure can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1.1 illustrates the change in UV spectra of a benzophenoneside-chain in polymer 2b (or 2 in Example V) with UV exposure time (365nm).

FIG. 1.2 illustrates an AFM image for the film of polymer 2b (or 2 inExample V) (122 nm) before sonication with an RMS roughness of 0.48 nm.

FIG. 1.3 illustrates an AFM image for the film of polymer 2b (or 2 inExample V) (65 nm) after sonication with RMS roughness of 0.83 nm.

FIG. 1.4 illustrates digital pictures of glass substrates that weresprayed with Staphylococcus. Aureus. (left) control slide and (right) 65nm thick polymer 2b.

FIG. 1.5 illustrates digital pictures of cotton strips that were sprayedwith Staphylococcus Aureus. (left) control and (right) substrate spraycoated with cross-linked polymer 2b.

FIG. 1.6 illustrates digital pictures of a polypropylene non-wovengeotextiles that were sprayed with Staphylococcus aureus. (left) controland (right) substrate spray coated with cross-linked polymer 2b.

FIG. 1.7 illustrates digital pictures of polyvinylchloride coatedpolyester grid structures that were sprayed with Staphylococcus aureus(left) control and (right) substrate sponge dabbed with cross-linkedpolymer 2b solution (15 mg/ml) and laundered.

FIG. 2.1 illustrates an FTIR spectra of top: Hytrel-4056; middle: Hytrelcoated with PEI copolymer; bottom: PEI copolymer.

FIG. 2.2 illustrates an FTIR spectra of top: PEI copolymer; middle:Petrothane coated with PEI copolymer; bottom: Petrothene.

FIG. 3.1 illustrates an FTIR spectra of a thin film of copolymer 2before (A) and after (B) UV exposure.

FIGS. 3.2A-B illustrate digital pictures of the glass substrates sprayedwith S. aureus and incubated for 24 hours at 37° C.: FIG. 3.2A is acontrol substrate and FIG. 3.2B is a glass substrate modified withpolymer 2 after sonication.

FIGS. 3.3A-B illustrate digital pictures of the glass substrates sprayedwith E. coli: FIG. 3.3A is a control substrate and FIG. 3.3B is glasssubstrate modified with 2 after sonication.

FIGS. 3.4A-H illustrate digital pictures of the textiles and plasticsubstrates sprayed with S. aureus: FIG. 3.4A, untreated cotton, FIG.3.4B, cotton sprayed coated with 15 mg/ml polymer 2, FIG. 3.4C,untreated polypropylene (nonwoven geotextile fabric), FIG. 3.4AD,polypropylene spray-coated with 15 mg/ml polymer 2, FIG. 3.4E, untreatedpoly(vinyl chloride) substrate, FIG. 3.4F, poly(vinyl chloride)substrate spray coated with 15 mg/ml polymer 2, FIG. 3.4G, untreatedpolyethylene substrate, and FIG. 3.4H, polyethylene substrate spraycoated with 15 mg/ml polymer 2.

FIG. 4.1 illustrates a proton NMR of ethylene-methyl acrylate copolymer(Optema TC115) coated with modified BP, coating to substrate ratio(33:100).

FIG. 4.2 illustrates a proton NMR of ethylene-methyl acrylate copolymer(Optema TC 115) coated with modified BP, coating to substrate ratio(5:100).

FIG. 4.3 illustrates a proton NMR of polyethylene (SABIC 2100) coatedwith modified BP, coating to substrate ratio (5:100).

FIG. 4.4 illustrates a proton NMR of ethyl vinyl acetate copolymer(Elvax® 460) coated with modified BP, coating to substrate ratio(5:100).

FIG. 5.1 illustrates two surfaces bound to one another bydiphenylmethoxy groups.

DETAILED DESCRIPTION

Before the present disclosure is described in greater detail, it is tobe understood that this disclosure is not limited to particularembodiments described, as such may, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present disclosure will be limited onlyby the appended claims.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present disclosure, the preferredmethods and materials are now described.

All publications and patents cited in this specification are hereinincorporated by reference as if each individual publication or patentwere specifically and individually indicated to be incorporated byreference and are incorporated herein by reference to disclose anddescribe the methods and/or materials in connection with which thepublications are cited. The citation of any publication is for itsdisclosure prior to the filing date and should not be construed as anadmission that the present disclosure is not entitled to antedate suchpublication by virtue of prior disclosure. Further, the dates ofpublication provided could be different from the actual publicationdates that may need to be independently confirmed.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features that may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentdisclosure. Any recited method can be carried out in the order of eventsrecited or in any other order that is logically possible.

Embodiments of the present disclosure will employ, unless otherwiseindicated, techniques of chemistry, polymer chemistry, biology, and thelike, which are within the skill of the art. Such techniques areexplained fully in the literature.

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how toperform the methods and use the compositions and compounds disclosed andclaimed herein. Efforts have been made to ensure accuracy with respectto numbers (e.g., amounts, temperature, etc.), but some errors anddeviations should be accounted for. Unless indicated otherwise, partsare parts by weight, temperature is in ° C., and pressure is inatmospheres. Standard temperature and pressure are defined as 25° C. and1 atmosphere.

Before the embodiments of the present disclosure are described indetail, it is to be understood that, unless otherwise indicated, thepresent disclosure is not limited to particular materials, reagents,reaction materials, manufacturing processes, or the like, as such canvary. It is also to be understood that the terminology used herein isfor purposes of describing particular embodiments only, and is notintended to be limiting. It is also possible in the present disclosurethat steps can be executed in different sequence where this is logicallypossible.

It must be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a support” includes a plurality of supports. In thisspecification and in the claims that follow, reference will be made to anumber of terms that shall be defined to have the following meaningsunless a contrary intention is apparent.

Definitions

The term “substituted” refers to any one or more hydrogens on thedesignated atom that can be replaced with a selection from the indicatedgroup, provided that the designated atom's normal valence is notexceeded, and that the substitution results in a stable compound.

The term “aliphatic group” refers to a saturated or unsaturated linearor branched hydrocarbon group and encompasses alkyl, alkenyl, andalkynyl groups, for example.

As used herein, “alkyl” or “alkyl group” refers to a saturated aliphatichydrocarbon chain and a substituted saturated aliphatic hydrocarbonchain which may be straight, branched, or cyclic, having 1 to 20 carbonatoms, where the stated range of carbon atoms includes each interveninginteger individually, as well as sub-ranges. Examples of alkyl groupsinclude, but are not limited to, methyl, ethyl, i-propyl, n-propyl,n-butyl, t-butyl, pentyl, hexyl, septyl, octyl, nonyl, decyl, and thelike. The substitution can be with a halogen, for example.

As used herein, “alkenyl” or “alkenyl group” refers to an aliphatichydrocarbon which can be straight or branched, containing at least onecarbon-carbon double bond, having 2 to 20 carbon atoms, wherein thestated range of carbon atoms includes each intervening integerindividually, as well as sub-ranges. Examples of alkenyl groups include,but are not limited to, ethenyl, propenyl, n-butenyl, i-butenyl,3-methylbut-2-enyl, n-pentenyl, heptenyl, octenyl, decenyl, and thelike.

The term “arylalkyl” refers to an arylalkyl group wherein the aryl andalkyl are as herein described. Examples of arylalkyl include, but arenot limited to, -phenylmethyl, phenylethyl, -phenylpropyl, -phenylbutyl,and -phenylpentyl.

The term “substituted,” as in “substituted alkyl”, “substitutedcycloalkyl,” “substituted cycloalkenyl,” substituted aryl,” substitutedbiaryl,” “substituted fused aryl” and the like means that thesubstituted group may contain in place of one or more hydrogens a groupsuch as hydroxy, amino, halo, trifluoromethyl, cyano, —NH(lower alkyl),—N(lower alkyl)₂, lower alkoxy, lower alkylthio, or carboxy, and thusembraces the terms haloalkyl, alkoxy, fluorobenzyl, and the sulfur andphosphorous containing substitutions referred to below.

As used herein, “halo”, “halogen”, or “halogen radical” refers to afluorine, chlorine, bromine, and iodine, and radicals thereof. Further,when used in compound words, such as “haloalkyl” or “haloalkenyl”,“halo” refers to an alkyl or alkenyl group in which one or morehydrogens are substituted by halogen radicals. Examples of haloalkylinclude, but are not limited to, trifluoromethyl, trichloromethyl,pentafluoroethyl, and pentachloroethyl.

The term “antimicrobial characteristic” refers to the ability to killand/or inhibit the growth of microorganisms. A substance having anantimicrobial characteristic may be harmful to microorganisms (e.g.,bacteria, fungi, protozoans, algae, and the like). A substance having anantimicrobial characteristic can kill the microorganism and/or preventor substantially prevent the growth or reproduction of themicroorganism.

The terms “bacteria” or “bacterium” include, but are not limited to,Gram positive and Gram negative bacteria. Bacteria can include, but arenot limited to, Abiotrophia, Achromobacter, Acidaminococcus, Acidovorax,Acinetobacter, Actinobacillus, Actinobaculum, Actinomadura, Actinomyces,Aerococcus, Aeromonas, Afipia, Agrobacterium, Alcaligenes, Alloiococcus,Alteromonas, Amycolata, Amycolatopsis, Anaerobospirillum, Anabaenaaffinis and other cyanobacteria (including the Anabaena, Anabaenopsis,Aphanizomenon, Camesiphon, Cylindrospermopsis, Gloeobacter Hapalosiphon,Lyngbya, Microcystis, Nodularia, Nostoc, Phormidium, Planktothrix,Pseudoanabaena, Schizothrix, Spirulina, Trichodesmium, and Umezakiagenera) Anaerorhabdus, Arachnia, Arcanobacterium, Arcobacter,Arthrobacter, Atopobium, Aureobacterium, Bacteroides, Balneatrix,Bartonella, Bergeyella, Bifidobacterium, Bilophila Branhamella,Borrelia, Bordetella, Brachyspira, Brevibacillus, Brevibacterium,Brevundimonas, Brucella, Burkholderia, Buttiauxella, Butyrivibrio,Calymmatobacterium, Campylobacter, Capnocytophaga, Cardiobacterium,Catonella, Cedecea, Cellulomonas, Centipeda, Chlamydia, Chlamydophila,Chromobacterium, Chyseobacterium, Chryseomonas, Citrobacter,Clostridium, Collinsella, Comamonas, Corynebacterium, Coxiella,Cryptobacterium, Delftia, Dermabacter, Dermatophilus, Desulfomonas,Desulfovibrio, Dialister, Dichelobacter, Dolosicoccus, Dolosigranulum,Edwardsiella, Eggerthella, Ehrlichia, Eikenella, Empedobacter,Enterobacter, Enterococcus, Erwinia, Erysipelothrix, Escherichia,Eubacterium, Ewingella, Exiguobacterium, Facklamia, Filifactor,Flavimonas, Flavobacterium, Francisella, Fusobacterium, Gardnerella,Gemella, Globicatella, Gordona, Haemophilus, Hafnia, Helicobacter,Helococcus, Holdemania lgnavigranum, Johnsonella, Kingella, Klebsiella,Kocuria, Koserella, Kurthia, Kytococcus, Lactobacillus, Lactococcus,Lautropia, Leclercia, Legionella, Leminorella, Leptospira, Leptotrichia,Leuconostoc, Listeria, Listonella, Megasphaera, Methylobacterium,Microbacterium, Micrococcus, Mitsuokella, Mobiluncus, Moellerella,Moraxella, Morganella, Mycobacterium, Mycoplasma, Myroides, Neisseria,Nocardia, Nocardiopsis, Ochrobactrum, Oeskovia, Oligella, Orientia,Paenibacillus, Pantoea, Parachlamydia, Pasteurella, Pediococcus,Peptococcus, Peptostreptococcus, Photobacterium, Photorhabdus,Phytoplasma, Plesiomonas, Porphyrimonas, Prevotella, Propionibacterium,Proteus, Providencia, Pseudomonas, Pseudonocardia, Pseudoramibacter,Psychrobacter, Rahnella, Ralstonia, Rhodococcus, Rickettsia RochalimaeaRoseomonas, Rothia, Ruminococcus, Salmonella, Selenomonas, Serpulina,Serratia, Shewenella, Shigella, Simkania, Slackia, Sphingobacterium,Sphingomonas, Spirillum, Spiroplasma, Staphylococcus, Stenotrophomonas,Stomatococcus, Streptobacillus, Streptococcus, Streptomyces,Succinivibrio, Sutterella, Suttonella, Tatumella, Tissierella,Trabulsiella, Treponema, Tropheryma, Tsakamurella, Turicella,Ureaplasma, Vagococcus, Veillonella, Vibrio, Weeksella, Wolinella,Xanthomonas, Xenorhabdus, Yersinia, and Yokenella. Other examples ofbacterium include Mycobacterium tuberculosis, M. bovis, M. typhimurium,M. bovis strain BCG, BCG substrains, M. avium, M. intracellulare, M.africanum, M. kansasii, M. marinum, M. ulcerans, M. avium subspeciesparatuberculosis, Staphylococcus aureus, Staphylococcus epidermidis,Staphylococcus equi, Streptococcus pyogenes, Streptococcus agalactiae,Listeria monocytogenes, Listeria ivanovii, Bacillus anthracis, B.subtilis, Nocardia asteroides, and other Nocardia species, Streptococcusviridans group, Peptococcus species, Peptostreptococcus species,Actinomyces israelii and other Actinomyces species, andPropionibacterium acnes, Clostridium tetani, Clostridium botulinum,other Clostridium species, Pseudomonas aeruginosa, other Pseudomonasspecies, Campylobacter species, Vibrio cholera, Ehrlichia species,Actinobacillus pleuropneumoniae, Pasteurella haemolytica, Pasteurellamultocida, other Pasteurella species, Legionella pneumophila, otherLegionella species, Salmonella typhi, other Salmonella species, Shigellaspecies Brucella abortus, other Brucella species, Chlamydi trachomatis,Chlamydia psittaci, Coxiella bumetti, Escherichia coli, Neiserriameningitidis, Neiserria gonorrhea, Haemophilus influenzae, Haemophilusducreyi, other Hemophilus species, Yersinia pestis, Yersiniaenterolitica, other Yersinia species, Escherichia coli, E. hirae andother Escherichia species, as well as other Enterobacteria, Brucellaabortus and other Brucella species, Burkholderia cepacia, Burkholderiapseudomallei, Francisella tularensis, Bacteroides fragilis,Fudobascterium nucleatum, Provetella species, and Cowdria ruminantium,or any strain or variant thereof. The Gram-positive bacteria mayinclude, but is not limited to, Gram positive Cocci (e.g.,Streptococcus, Staphylococcus, and Enterococcus). The Gram-negativebacteria may include, but is not limited to, Gram negative rods (e.g.,Bacteroidaceae, Enterobacteriaceae, Vibrionaceae, Pasteurellae andPseudomonadaceae). In an embodiment, the bacteria can include Mycoplasmapneumoniae.

The term “protozoan” as used herein includes, without limitationsflagellates (e.g., Giardia lamblia), amoeboids (e.g., Entamoebahistolitica), and sporozoans (e.g., Plasmodium knowlesi) as well asciliates (e.g., B. coli). Protozoan can include, but it is not limitedto, Entamoeba coli, Entamoeabe histolitica, Iodoamoeba buetschlii,Chilomastix meslini, Trichomonas vaginalis, Pentatrichomonas homini,Plasmodium vivax, Leishmania braziliensis, Trypanosoma cruzi,Trypanosoma brucei, and Myxoporidia.

The term “algae” as used herein includes, without limitations microalgaeand filamentous algae such as Anacystis nidulans, Scenedesmus sp.,Chlamydomonas sp., Clorella sp., Dunaliella sp., Euglena sp., Prymnesiumsp., Porphyridium sp., Synechoccus sp., Botryococcus braunii,Crypthecodinium cohnii, Cylindrotheca sp., Microcystis sp., Isochrysissp., Monalianthus salina, M. minutum, Nannochloris sp., Nannochloropsissp., Neochloris oleoabundans, Nitzschia sp., Phaeodactylum tricornutum,Schizochytrium sp., Senedesmus obliquus, and Tetraselmis sueica as wellas algae belonging to any of Spirogyra, Cladophora, Vaucheria,Pithophora and Enteromorpha genera.

The term “fungi” as used herein includes, without limitations, aplurality of organisms such as molds, mildews and rusts and includespecies in the Penicillium, Aspergillus, Acremonium, Cladosporium,Fusarium, Mucor, Nerospora, Rhizopus, Tricophyton, Botryotinia,Phytophthora, Ophiostoma, Magnaporthe, Stachybotrys and Uredinalisgenera.

As used herein, the term “fiber” refers to filamentous material that canbe used in fabric and yarn as well as textile fabrication. One or morefibers can be used to produce a fabric or yarn. Fibers include, withoutlimitation, materials such as cellulose, fibers of animal origin (e.g.,alpaca, angora, wool and vicuna), hemicellulose, lignin, polyesters,polyamides, rayon, modacrylic, aramids, polyacetates, polyxanthates,acrylics and acrylonitriles, polyvinyls and functionalized derivatives,polyvinylidenes, PTFE, latex, polystyrene-butadiene, polyethylene,polyacetylene, polycarbonates, polyethers and derivatives,polyurethane-polyurea copolymers, polybenzimidazoles, silk, lyocell,carbon fibers, polyphenylene sulfides, polypropylene, polylactides,polyglycolids, cellophane, polycaprolactone, “M5” (poly{diimidazopyridinylene (dihydroxy) phenylene}), melamine-formadehyde, plastarch,PPOs (e.g., Zylon®), polyolefins, and polyurethane.

The term “textile article” can include garments, fabrics, carpets,apparel, furniture coverings, drapes, upholstery, bedding, automotiveseat covers, fishing nets, rope, articles including fibers (e.g.,natural fibers, synthetic fibers, and combinations thereof), articlesincluding yarn (e.g., natural fibers, synthetic fibers, and combinationsthereof), and the like.

Discussion:

In accordance with the purpose(s) of the present disclosure, as embodiedand broadly described herein, embodiments of the present disclosure, inone aspect, relate to polymer compositions, methods of making polymercompositions, structures having the polymer composition covalentlybonded to the surface of the structure, methods of attaching the polymerto the surface of the structure, methods of decreasing the amount ofmicroorganisms formed on a structure, and the like. In an embodiment,the polymer composition (or the polymer disposed on a surface) may havean antimicrobial characteristic (e.g., kills at least 70%, at least 80%,at least 90%, at least 95%, or at least 99% of the microorganisms (e.g.,bacteria) on the surface and/or reduces the amount of microorganismsthat form or grow on the surface by at least 70%, at least 80%, at least90%, at least 95%, or at least 99%, as compared to a similar surfacewithout the polymer composition disposed on the surface). In anembodiment, the polymer composition (or the polymer disposed on asurface of a structure) may not have an antimicrobial characteristic.Additional details are described in Examples I to VI.

In an embodiment, the structures can include those that may be exposedto microorganisms and/or that microorganisms can grow on such as,without limitation, fabrics, cooking counters, food processingfacilities, kitchen utensils, food packaging, swimming pools, metals,drug vials, medical instruments, medical implants, yarns, fibers,gloves, furniture, plastic devices, toys, diapers, leather, tiles, andflooring materials. The structures may also include live biologicstructures (or surfaces of live biologic structures) such as seeds foragricultural uses, tree limbs, and trunk, as well as teeth. In anembodiment, the structure inherently includes C—H groups on the surfaceof the structure to interact with the polymer, as described below. In anembodiment, the structure includes a functionalized layer disposed onthe structure that includes the C—H groups on the surface to interactwith the polymer. In an embodiment, the structure can include surfacesthat inherently include C—H groups on the surface of the structure andalso can include surfaces that include a functionalized layer disposedon the structure that includes the C—H groups. In an embodiment, thefunctionalized layer can have a thickness of about 2 nanometers (nm) to1 micrometer (μm) or about 25 nm to 120 nm.

In an embodiment, the structure can include textile articles, fibers,filters or filtration units (e.g., HEPA for air and water), packagingmaterials (e.g., food, meat, poultry, and the like food packagingmaterials), plastic structures (e.g., made of a polymer or a polymerblend), glass or glass like structures having a functionalized layer(e.g., includes a C—H group) on the surface of the structure, metals,metal alloys, or metal oxides structure having a functionalized layer(e.g., includes a C—H group) on the surface of the structure, astructure (e.g., tile, stone, ceramic, marble, granite, or the like)having a functionalized layer (e.g., includes a C—H group) on thesurface of the structure, and a combination thereof. In an embodiment,the structure includes structures used in the fishing industry and theseinclude fishing nets, fishing gear and tackle, fish, crab or lobstercages, and the like.

In an embodiment, the polymer is covalently bonded via the interactionof the polymer with a UV light (e.g., about 340 to 370 nm) that causes aC—C bond to form between the polymer and the surface having a C—H groupor a layer on the surface having the C—H group. In other words, thepolymer can be attached to the surface or the layer on the surfacethrough a photochemical process so the bonding is easy and inexpensiveto achieve. Once the covalent bonds are formed, the polymer layer isstrongly bound to the surface and can withstand very harsh conditionssuch as sonication and extended washing steps as well as exposure toharsh environmental conditions (e.g., heat, cold, humidity, lake, river,and ocean conditions (e.g., above and/or under water), and the like).

In an embodiment, the polymer (also referred to as a “polymercomposition”) includes a linear or branched polyethyleneimine polymerthat has been quaternized with a hydrophobic side chain moiety and aphoto cross-linkable moiety. In an embodiment, the molar ratio betweenhydrophobic side chain moiety and photo cross-linkable moiety can beabout 99:1 to 10:90 including about 20:80, about 30:70, about 50:50,about 70:30, about 80:20, ranges between each of these and other ratiosin between. In an embodiment, the polyethyleneimine polymer is a linearpolyethyleneimine polymer that can include secondary amines. In anembodiment, the polyethyleneimine polymer is a branchedpolyethyleneimine polymer that can include primary, secondary, and/ortertiary amino groups.

In an embodiment, the polymer can have the following structure

The polyethyleneimine polymer can be linear or branched. R1 is ahydrophobic side chain moiety and is B a photo cross-linkable moiety. Ais a counter ion and R2 is a linking moiety such as a hydrocarbon carbonchain (e.g., saturate or unsaturated, and optionally substituted).

In an embodiment, the polymer can have the following structure (Scheme1):

Example of Possible Branching Structures in Branched Copolymer

The above structure is for illustrative, non-limiting purposes. Thestructure of the polymer may take on other branching patterns, orcomprise single or multiple sites for attachment to surfaces through aphotochemical reaction. Schemes 2-3 below illustrate the formation of apolymer and attachments to a surface. Scheme 4 below describes how thepolymer attaches to a surface. Additional details are provided inExamples I to VI.

In an embodiment, the counter anion (e.g., A) on quaternary aminepolymers can include different anions such as chloride, bromide, iodide,alkyl sulfate anions (e.g., methyl sulfate, ethyl sulfate,dodecylsulfate), tetrafluoroborate, and tosylate.

In an embodiment, the polymer composition that includes a linear orbranched polyethyleneimine polymer that has been quaternized with ahydrophobic side chain moiety and a photo cross-linkable moiety, isblended with another, secondary polymer to form a polymer blend that canbe directly used to manufacture polymers or polymer-based items or as asurface treatment, wherein (i) the secondary polymer can be anythermosetting or thermoplastic polymer, a finish material such as aresin or an adhesive, or other polymer cited herein or (ii) thesecondary polymer of (i) may include an optional colored pigment.

In an embodiment, the polymer can have a molecular weight of about 20kilodaltons to 5000 kilodaltons. In an embodiment, the polymer can havea molecular weight of about 50 kilodaltons to 1000 kilodaltons. In anembodiment, the polymer can have a molecular weight of about 50kilodaltons to 500 kilodaltons. In an embodiment, the polymer can have amolecular weight of about 50 kilodaltons to 250 kilodaltons. In anembodiment, the polymer can have a molecular weight of about 50kilodaltons to 150 kilodaltons. In an embodiment, the polymer can have amolecular weight of about 100 kilodaltons to 150 kilodaltons.

In an embodiment, the hydrophobic side chain moiety (e.g., R1) functionsto at least provide a hydrophobic characteristic to the polymer. In anembodiment, the hydrophobic side chain can include a hydrocarbon chainsuch as: octane or its derivatives (e.g., 2-ethylhexane,3-(methyl)heptane, 6-methylheptane, 2-methylheptane), decane or itsderivatives (e.g., 3, 7-dimethyl octane, 7-methyl nonane), dodecane orits derivatives (e.g., 4,8-dimethyl decane, 2-methyl undecane, 3-methylundecane, 9-methyl undecane, 10-methyl undecane), tridecane or itsderivatives (e.g., 2-methyl dodecane, 3-methyl dodecane, 6-methyldodecane, 7-methyl dodecane, 8-methyl dodecane, 9-methyl dodecane,10-methyl dodecane, 11-methyl dodecane), pentadecane or its derivatives(e.g., 3, 7, 11-trimethyl dodecane, 13-methyl tetradecane), hexadecaneor its derivatives (e.g., 7-(methyl) pentadecane, 7-(3-propyl)tridecane), heptadecane or its derivatives (e.g., 11-methyl hexadecane,14-methyl hexadecane, 2-methyl hexadecane), octadecane or itsderivatives (e.g., 11-methyl heptadecane), nonadecane or its derivatives(e.g. 14-methyl octadecane) eicosane or its derivatives (e.g., 3, 7, 11,15-tetramethyl hexadecane, 9-(3-propyl) heptadecane), heneicosane or itsderivatives (e.g., 20-methylheneicosane), docosane or its derivatives(e.g., 20-methyl heneicosane), tetraconsane (e.g., 11-methyl tricosane),and a combination thereof, where the combination can include a polymerthat includes two or more different hydrophobic side changes. In anembodiment, one or more of the hydrocarbon chains can be substituted. Inan embodiment, at least one C—H bond in the position alpha to theammonium group can be replaced by an electronegative group selected fromthe group consisting of F, CI, and Br. Examples of hydrophobic sidechain moieties are described in Example I. In an embodiment, thehydrophobic side chain moiety can include a C═C group in the chain(e.g., at the terminal end). In an embodiment, the hydrophobic sidechain moiety can have an alkene group attached to it so that the carbonchain includes one or more C═C bonds.

In an embodiment, the photo cross-linkable moiety (e.g., B) functions toat least undergo a photochemical change to covalently bond with asurface or a layer on the surface of a structure having a C—H group. Inan embodiment, the polymer composition is covalently bonded via theinteraction of the polymer with a UV light (e.g., about 250 nm to 500 nmor about 340 to 370 nm) that causes a C—C bond to form between thepolymer and the surface or a layer on the surface having the C—H group.The UV light can be generated from a UV light source such as those knownin the art.

In an embodiment, the photo cross-linkable moiety can include an arylketone (about 340 to 400 nm), an aryl azide group (about 250 to 450 nmor about 350 to 375 nm), a diazirine group (about 340 to 375 nm), andthe polymer can include a combination of these groups. In an embodiment,the photo cross-linkable moiety can include alkyl-arylketones anddiarylketones bearing at least one condensed ring system substituentsuch as naphtyl and anthracenyl (See Example IV). In an embodiment, thearyl ketone group can include benzophenone (about 340 to 380 nm),acetophenone (about 340 to 400 nm), a naphthylmethylketone (about 320 to380 nm), a dinaphthylketone (about 310 to 380 nm), a dinaphtylketonederivative (about 320 to 420 nm), or derivatives of each of these. In anembodiment, the photo cross-linkable moiety is a benzophenone group. Inan embodiment, the aryl azide group can include phenyl azide, alkylsubstituted phenyl azide, halogen substituted phenyl azide, orderivatives of each of these. In an embodiment, the diazirine group caninclude 3,3 dialkyl diazirine (e.g., 3,3 dimethyl diazirine, 3, 3diethyl diazirine), 3,3 diaryl diazirine (e.g., 3,3 diphenyl diazirine),3-alkyl 3-aryl diazirine, (e.g., 3-methyl-3-phenyl diazirine), orderivatives of each of these. Additional examples are described in FIG.1.4.

As mentioned above, the polymer can be disposed on a surface to producea structure that includes the polymer covalently bonded (via aphotochemical process) to the surface of the structure. In anembodiment, the method of disposing the polymer on the surface of thestructure includes disposing the polymer on the surface using a methodsuch as spraying, dipping, painting, spin coating, drop casting, and thelike. In an embodiment, the surface of the structure has C—H groups thatcan interact (e.g., form C—C bonds) with the polymer upon exposure to UVlight. In an embodiment, the structure has a layer (also referred to asa “functionalized layer”) (e.g., a thin film or self assembling layer)disposed on the surface of the structure. The functionalized layerincludes C—H bonds that can interact (form C—C bonds) with the polymerupon exposure to UV light. Additional details are described in theExamples. The structure can be exposed to UV light in many differentways such as direct exposure to a UV light source, exposure to UV lightduring the spray coating process, exposure to UV light during the dipcoating process, exposure to UV light during the spincoating process,exposure to UV light during dip padding, exposure to UV light during nippadding, exposure to UV light during kiss rolling, and exposure to UVlight during the drop-casting process.

Either during application of the polymer or once the polymer is disposedon the surface, UV light is directed onto the polymer on the surface. Asdescribed above, the UV light causes a photochemical reaction to occurbetween the polymer and the surface to form one or more covalent bonds(C—C bonds) between the polymer and the surface.

The wavelength of the UV light can be selected based on the photocross-linkable moiety. In general, the UV light can be active to formthe C—C bonds at about 190 to 500 nm, about 190 to 350, about 340 to 400nm, or about 360 to 370 nm. The specific wavelength(s) that can be usedfor a particular photo cross-linkable moiety are described herein. In anembodiment, the UV light can be active to form the C—C bonds at awavelength of about 340 to 370 nm. In an embodiment, the UV light can beactive to form the C—C bonds at a wavelength of about 365 nm.

In an embodiment, after the polymer is covalently bonded to the surface,the structure may have an antimicrobial characteristic that is capableof killing a substantial portion of the microorganisms (e.g., bacteria)on the surface of the structure and/or inhibits or substantiallyinhibits the growth of the microorganisms on the surface of thestructure. The phrase “killing a substantial portion” includes killingat least about 70%, at least about 80%, at least about 90%, at leastabout 95%, or at least about 99% of the microorganism (e.g., bacteria)on the surface that the polymer is covalently bonded, relative tostructure that does not have the polymer disposed thereon. The phrase“substantially inhibits the growth” includes reducing the growth of themicroorganism (e.g., bacteria) by at least about 70%, at least about80%, at least about 90%, at least about 95%, or at least about 99% ofthe microorganisms on the surface that the polymer is covalently bonded,relative to a structure that does not have the polymer disposed thereon.

In an embodiment, once the structure has the polymer layer disposed onthe entire surface or select portions of the surface, the structure canbe exposed to the environment for which the structure is to be used. Inan embodiment, the structure is used in the ocean, river, stream,collection pond, or lake. The structure can be introduced into the waterand over a period of time the structure should have a smaller amount ofmicroorganisms disposed on the structure relative to a structure withoutthe polymer layer. Periodically, the structure can be exposed to thepolymer material again to ensure that the previous polymer layer was notremoved due to normal wear.

EXAMPLES Example I

Experimental Materials

Silicon wafers (UniversityWafer.com) with native oxide and glass slides(VWR) (cut into 3.8×2.5 cm pieces) were used as substrates.Poly(2-ethyl-2-oxazoline) (Aldrich), tert-amylalcohol (Aldrich),1-bromododecane (Alfa Aesar), iodomethane (Alfa Aesar),4-hydroxybenzophenone (Alfa Aesar), 1, 6 dibromohexane (Alfa Aesar),were used as received.

Instrumental Methods

AFM experiments were performed using a Multimode Nanoscope IIIa (DigitalInstruments/Veeco Metrology Group). All measurements were performedusing tapping mode. Null ellipsometry was performed on a Multiskop(Optrel GbR) with a 632.8 nm He—Ne laser beam as the light source. Bothδ and ψ value thickness data were measured and calculated by integratedspecialized software. At least three measurements were taken for everylayer, and the average thickness was calculated.

Synthesis

Linear Polyethyleneimine (PEI):

The deacylation reaction was performed according to literature procedure(PNAS, 2005, 102, 5679). 3 g of the Poly(2-ethyl-2-oxazoline, M_(w), 50kDa) (POEZ) was added to 120 mL of 24% (wt/vol) HCl, followed byrefluxing for 96 h. The POEZ crystal dissolved completely in 1 h, butafter overnight reflux, a white precipitate appeared. The precipitatewas filtered and then air-dried. The resultant protonated PEI wasdissolved in water and neutralized with aqueous KOH to precipitate thepolymer. The white powder was isolated by filtration, washed withdistilled water until the pH of the washed liquid became neutral, anddried under vacuum. Yield: 1.15 g (88%). ¹H NMR (CDCl₃): δ, 2.72 (s, 4H,NCH₂CH₂N), 1.71 (1H, NH).

Linear N,N-dodecyl methyl PEI:

The linear quaternized PEI was synthesized according to the literatureprocedure (PNAS, 2006, 103, 17667). 1 g (23.5 mmol of the monomer unit)of the PEI was dissolved in 12 mL of tert-amyl alcohol, followed by theaddition of 3.85 g (28.5 mmol) of K₂CO₃, and 16.5 mL (67 mmol) of1-bromododecane, and the reaction mixture was stirred at 95° C. for 96h. After removing the solids by filtration under reduced pressure, 2.8mL of iodomethane was added, followed by string at 60° C. for 24 h in asealed fluxed. The resultant solution was added to excess ofethylacetate; the precipitate formed was recovered by filtration underreduced pressure, washed with excess of ethylacetate and dried at roomtemperature under vacuum overnight. Yield: 3.2 g.

4-[(6-Bromohexyl)oxy]benzophenone

4-Hydroxy benzophenone (5.94 g, 30 mmol), 1,6 dibromohexane (8.05 g, 33mmol), potassium carbonate (5.95 g, 45 mmol) and DMF (60 mL) werestirred at room temperature for 16 h under inert atmosphere. Thereaction mixture was poured into ice water (300 mL) and extracted withether (100 mL). The organic layer was collected and the solvent wasremoved by rotary evaporator. The crude product was purified on silicagel column by using 10:1 hexane ethylacetate mixture. Yield: 8.2 g(76%). ¹H NMR (CDCl₃): δ, 7.81 (d, 2H, J=8.4 Hz), 7.75 (d, 2H, J=7.8Hz), 7.54 (t, 1H, 7.5 Hz), 7.47 (t, 2H, J=6.9 Hz), 6.93 (d, 2H, J=9.0Hz), 4.06 (t, 2H, J=6.3 Hz), 3.43 (t, 2H, 6.6 Hz), 1.86 (m, 4H), 1.50(m, 4H). ¹³C NMR (CDCl₃): δ, 25.47, 28.10, 29.11, 32.86, 33.95, 68.2,114.2, 128.37, 129.92, 129.94, 132.06, 132.78, 138.55, 162.9, 195.7.

1,6-Bis (4-benzoylphenoxy)hexane

4-Hydroxy benzophenone (5.94 g, 30 mmol), 1,6 dibromohexane (3.66 g, 15mmol), sodium hydroxide (1.8 g, 45 mmol) and DMF (30 mL) were refluxedfor 6 h under inert atmosphere. The reaction mixture was cooled at roomtemperature, poured into ice water (300 mL) and extracted with ether(100 mL). The organic layer was collected and the solvent was removed byrotary evaporator. The crude product was purified on silica gel columnby using 10:1 hexane ethylacetate mixture. Finally compound wascrystallized from DCM/hexane solvent mixture. Yield: 5.1 g (71%). ¹H NMR(CDCl₃): δ, 7.82 (d, 4H, J=7.7 Hz), 7.75 (d, 4H, J=7.5 Hz), 7.56 (t, 2H,7.2 Hz), 7.47 (t, 4H, J=7.2 Hz), 6.95 (d, 4H, J=9.0 Hz), 4.06 (m, 4H),1.87 (br, 4H), 1.55 (br, 4H). ¹³C NMR (CDCl₃): δ, 26.06, 29.28, 43.52,114.19, 114.22, 128.38, 129.90, 129.92, 132.06, 132.78, 138.72, 162.97.

Linear Copolymer of N,N-dodecyl methyl andN,N-[(6-hexyl)oxy]benzophenone methyl PEI:

0.5 g (12 mmol of the monomer unit) of the PEI was dissolved in 6 mL oftert-amyl alcohol, followed by the addition of 2.1 g (15 mmol) of K₂CO₃,1.97 g (8 mmol) of 1-bromododecane, and 1.44 g of4-[(6-bromohexyl)oxy]benzophenone and the reaction mixture was stirredat 95° C. for 96 h. After removing the solids by filtration underreduced pressure, 1.5 mL of iodomethane was added, followed by string at60° C. for 24 h in a sealed fluxed. The solution was dried under rotaryevaporator. The yellow solid was dissolve in minimum volume ofdichloromethane and then added excess hexane to precipitate the polymer.Light yellow solid was filtered and dried at room temperature undervacuum for overnight. Yield: 2.3 g (46%). ¹H NMR (CDCl₃): δ, 7.76 (bs,4H); 7.56 (bs, 1H), 7.45 (bs, 2H); 6.98 (bs, 2H); 4.91-3.26 (m, 21H);1.82 (bs, 6H); 1.65 (bs, 16H); 1.23 (bs, 34H), 0.66 (bs, 6H).

Preparation of Self-Assembled Monolayers (SAM) on Glass Substrates:

Glass slides were cut into rectangles. The substrates were sonicatedwith Fisherbrand sonicating soap, 18.2 MΩ deionized water, isopropanol,and acetone for 10 min each and finally dried in an oven for 1 h. Aftercleaning, a self-assembled monolayer of 7-octenyl trichlorosilane wasformed from the vapor phase by suspending the substrates in a vacuumdessicator and placing two drops of silane on a glass substrate at thebottom. The substrates were kept in a vacuum flux constant pressure (100millitorr) for 20 min. After venting with nitrogen, the substrates weresonicated with acetone and dried under air.

Surface Bound PEI Polymer (2a):

15 mg of quaternized PEI polymer and 10 mg of dibenzophenone wasdissolved in 1 mL of chloroform solvent. The solution was filteredthrough 0.25 μm filter. The polymer film was developed on functionalizedglass substrate by spin coating with 0.5 mL of solution at 1000 rpm. Theglass substrate was radiated with UV light (360 nm, 180 mW/cm²) for 15minutes to covalently bound the polymer on glass surface withbenzophenone as linker. The substrate was sonicated with acetone for onemin and dried under air.

Surface Bound PEI Polymer (2b):

15 mg of quaternized polymer (2b) was dissolved in 1 mL of chloroformsolvent. The solution was filtered through 0.25 μm filter. The polymerfilm was developed on functionalized glass substrate by spin coatingwith 0.5 mL of solution at 1000 rpm. The glass substrate was radiatedwith UV light (360 nm, 180 mW/cm²) for 15 mins to covalently bound thepolymer on glass surface with benzophenone as linker. The substrate wassonicated with acetone for one min and dried under air.

It will be recognized that the general process described in Scheme 4 canalso be used to modify a silicate-based surface to render it with novelproperties. For instance, if oligomers or polymers of, for instance,vinylfluoride (—H₂C—CHF—)_(x), or tetrafluoroethylene (—CF₂—CF₂—)_(y)are used instead of PEI, in a process similar to that in Scheme 4, asilicate surface could be rendered hydrophobic after undergoing covalentattachment of benzophenone-(fluorocarbon) copolymer.

Antimicrobial Test Method:

Trypticase Soy Broth (TSB) (10 ml) was inoculated with one loopful ofStaphylococcus aureus culture and incubated overnight in a water shakerbath at 37° C. with 45 linear strokes per minute (TSB contains 17 g ofcasein peptone, 3 g of soy meal peptone, 2.5 g of D-(+) glucose, 5 g ofNaCl and 2.5 g of dipotassium hydrogen phosphate per liter). 100 μl ofan overnight Staphylococcus aureus culture was again inoculated with 10ml of TSB and incubated for 4 hours in above mentioned conditions in theshaker bath. From freshly prepared 4 hour microbe culture 1 ml wastransferred to 1.5 ml centrifuge tube. The tube was centrifuged at 5000rpm for 1 minute at 21° C. (Centrifuge=accuSpin Micro 17R, FisherScientific, Tubes=Micro Centrifuge Tube, VWR International). Thesupernatant solution was discarded and fresh 1 ml of sterile water wasadded to the precipitated microbe tube. The microbes were re-suspendedin the solution by using vortex mixer (Vortex Mixer=Vortex Genie 2).This re-suspended solution was transferred to 9 ml sterile water. There-suspended solution was diluted ten times to get ˜3.4×10⁶ colonyforming units/ml (CFU/ml). Approximately 5 ml of this diluted solutionwas transferred to TLC sprayer bottle. The TLC sprayer bottle wasconnected to EFD (1500XL) pneumatic dispense regulator. The polymercoated substrates were uniformly sprayed in a controlled fashion fromthe TLC sprayer for 1 second at 30-40 psi pressure. The distance betweenthe sprayer and glass slide was approximately 1½ feet. The sprayedsample was air dried for approximately 2 minutes and carefully mounted asprayed surface of the sample on a Difco™ Trypticase Soy Agar (TSA)plate (TSA contains 15.0 g of pancreatic digest of casein, 5.0 g ofenzymatic digest of soyabean meal, 5.0 g of sodium chloride, and 15.0 gof agar per liter). TSA plates were incubated for 24 hours at 37° C.Finally the number of colonies grown on the slide was observed.

Launder-O-Meter Testing:

Approximately 1 sq inch of net samples was used for testing. The netsample was coated with 15 mg/ml of polymer 2b dissolved in acetone. Thedissolved polymer solution was applied through spray coating and dabbingpolymer solution soaked sponge on the both sides of net samples.Uncoated sample was used as control. Three replications were done forcoated sample. Each sample was treated with 150 ml of 35 gpl(gram/liter) saline solution (NaCl) along with 50 steel balls (6 mm indiameter). The treatment was given in a closed stainless steel canister(500 ml, 75×125 mm) on an Atlas Launder-o-meter (AATCC standardinstrument) at 49° C. for 45 minutes. The samples were rinsed with waterand were tested for antibacterial efficacy.

Result and Discussions

Two quaternary amine polymer have been synthesized (2a and 2b) (FIG.1.1) with (2b) and without (2a) attachment of a benzophenone moiety.Polymer 2a was synthesized according to the literature procedure(Proceedings of the National Academy of Science 2006, 103, 17667-17671,which is incorporated by reference). Another polymer 2b was prepared byreacting PEI polymer with 4-[(6-Bromohexyl)oxy]benzophenone and1-bromododecane. The copolymer composition was checked by NMRspectroscopy, which revealed that the polymer composition matched themonomer feed ratio. Polymer 2a is soluble in halogenated solvents butinsoluble in alcohols, where as polymer 2b is soluble in halogenatedsolvents and slightly soluble in alcohols. Polymer 2b is also readilysoluble in acetone. Our strategy is to photochemically attach thepolymer material onto the surface by using the benzophenone (BP) moietyas a cross-linker. Benzophenone is an ideal candidate for cross-linkingbecause it is (1) useful for any organic surface or surfacefunctionalized with an organic molecule which has a C—H bond; (2) it canbe activated using very mild UV light (˜345-360 nm), avoiding oxidativedamage to the polymer and substrate by exposure to shorter wavelengths.(3) Benzophenone is chemically more stable than other organiccrosslinkers and reacts preferentially with C—H bonds in a wide range ofdifferent chemical environments. Triggered by UV light, benzophenone hasan n-π* transition, resulting in the formation of a biradical tripletexcited state that then abstracts a hydrogen atom from neighboringaliphatic C—H group to form a new C—C bond.

While this mechanism provides the ability to coat any type of polymericsurface, we have used glass surfaces and silicon wafers to do thepreliminary biocidal experiments because of the ease of surfaceanalytical quantification. These substrates allow us to measure coatingthickness and to observe changes in surface morphology upon irradiationwith UV light. The substrates are coated with a self-assembled monolayerof organic silane to provide reactive C—H groups that will mimic plasticfunctionalization, while retaining very low roughness for accuratemeasurements of thickness. Fabrication of covalently bound polymersurfaces is shown in Scheme 3 and 4. In both cases, glass or siliconsurfaces were functionalized with octyltrichlorosilane to generate C—Hgroups on the surface. This can be done with any trichloro-,trimethoxy-, or triethoxy-alkylsilane derivative. To this modifiedsurface a thin layer of polymer 2a with dibenzophenone (Scheme 3) orpolymer 2b was applied using a spin coater. This was to ensure smoothcoating and a uniform film thickness. In the last step, the desiredcovalently attached films were generated by crosslinking through thebenzophenone group with UV irradiation. To remove unbound materials,films were washed with acetone or sonicated in acetone for one minute.The thicknesses were measured for polymer film 2b before and aftersonication and were 122 and 65 nm respectively. It is important to notethat the polymers will covalently attach to any organic substrates witha C—H bond (examples are cotton, polyethylene, polypropylene, or othercommon plastics). In these cases, the covalently attached polymersurface can be generated without any functionalization because of thepresence of C—H group on the surface.

The kinetics of surface attachment of the PEI copolymers with differentirradiation times was investigated by UV-vis spectroscopy. Changes inthe absorption spectra of the polymer film with 2b under UV lightirradiation are shown in FIG. 1.1. Focusing on the BP photophore,absorption of a photon at 350 nm results in the promotion of oneelectron from a nonbonding sp² to an antibonding π*-orbital of thecarbonyl group. In the diradicaloid triplet state, theelectron-deficient oxygen n-orbital is electrophilic and thereforeinteracts with weak C—H δ-bonds, resulting in hydrogen (H) abstractionto complete the half-filled n-orbital. To confirm the photochemicalattachment, we investigated the absorption spectroscopy with UVirradiation time. The π-π* absorption of benzophenone at 290 nmdecreases with increasing irradiation time, indicating the decompositionof carbonyl group through the above photochemical reaction.

Atomic force microscopy (AFM) was use to characterized the surfacemorphology of polymer (2b) film before and after sonication to removeany non-covalently bound polymer from the surface. Before sonication,the polymer film was very smooth. A representative morphology for thefilm before sonication is shown by FIG. 1.2, which has an RMS roughness0.48 nm. This is approximately the roughness of the glass substrate(0.39 nm) before functionalization. FIG. 1.3 shows the AFM image of thefilm after sonication. Though the basic morphology of surfaces are samebefore and after sonication, the roughness (0.83 nm) has slightlyincreased with sonication due to the removal of any non-covalentlyattached polymer from the surface. The AFM measurements, along with thethickness values measured with ellipsometry confirm the attachment ofthe polymer to the substrate surface.

The ability of the polymer-coated surfaces to kill bacteria was testedfor different textile woven and non-woven fabrics and glass substrates.The density of the quaternized amine polymer played an important role inthe biocidal activity (Table 1). We examined the surfaces with a coatingvarying from 10 to 65 nm in thickness. The surface grafted with a highdensity of polymers exhibited relatively high biocidal activity. Whenthe thickness of the polymer layer is greater than 50 nm, essentiallyall the bacteria are killed. FIG. 1.4 shows the digital photograph ofthe control and polymer functionalized surfaces incubated with bacteria.As seen in FIG. 1.4a , numerous colonies of S. aureus grown on thecontrol slide after spraying the bacterial suspension onto its surface.On the other hand no colonies were found on the polymer functionalizedsurface (FIG. 1.4b ).

TABLE 1 There were four sets of samples tested: 1. Control Glass, 2.Spin coated glass slide with 5 mg/ml polymer concentration, 3. Spincoated glass slide with 10 gm/ml polymer, and Spin coated glass slidewith 15 mg/ml concentration. The different concentrations allow controlover different thickness values. The copolymer (2b) was spin coated onthe glass sample and UV irradiated with 360 nm light of an intensity 180mW/cm² and then sonicated for 1 minute. The coated and control sampleswere sprayed with S. aureus solution. TMTC~too many to count. 15 mg/ml 5mg/ml 10 mg/ml polymer Control Polymer coated Polymer coated coated Rep.glass Glass (22 nm) Glass (50 nm) glass (65 nm) 1 TMTC 30 15 0 2 TMTC 4218 0 3 TMTC 29 12 0

TABLE 2 There were four sets tested 1. Control cotton sample, 2. Polymerspray coated cotton sample without UV radiation, 3. Polymer spray coatedcotton sample with UV radiation, and 4. Polymer spray coated cottonsample with UV radiation and acetone washed. Microbe Tested:Staphylococcus aureus (gram positive bacteria). Digital images are shownin FIG. 1.5. No UV UV radiation & Acetone radiation No wash washedControl (Polymer conc. (Polymer conc. (Polymer conc. Rep. Cotton 15mg/ml) 15 gm/ml) 15 gm/ml) 1 TMTC 10 0 7 2 ~150 6 5 0 3 ~300 0 8 1Average   225 8 6.5 4 % Reduction — 96.44 97.11 98.22

TABLE 3 There were two sets tested with Escherichia coli (gram negativebacteria) 1. Control glass slide and 2. Glass substrate with 65 nm thickpolymer 2b. Control Rep. Glass Substrate 1 ~280 0 2 TMTC 0 3 ~100 0Average   190 0 % Reduction — 100

TABLE 4 There were three sets tested: 1. Control polypropylene substrate(Ten Cate Nicolon geosynthetic product), 2. Polymer spray coated and UVirradiated sample and 3. Polymer spray coated, UV irradiated and acetonewashed sample. Microbe Tested: Staphylococcus. aureus (gram positivebacteria). Digital pictures are shown in FIG. 1.6. UV radiated Rep.Control UV radiated Acetone washed 1 TMTC 6 31 2 TMTC 7 — 3 TMTC 12 —Launder-o-meter testing: The durability of coating was analyzed throughlaunder-o-meter test. There were three different sets of substrates usednamely, (1) PVC coated net samples as a control, (2) PVC net coatedsamples coated with polymer 2b and UV radiated and (3) PVC net coatedsamples coated with polymer 2b and UV radiated and laundered using abovementioned procedure. The laundered sample showed less microbial growthcompared to control samples. The number of colonies on samples was notcountable. The digital pictures are shown in FIG. 1.7.

Example II

Testing in aquatic environments: The effectiveness of the polymercoating on polyvinylchloride substrates was tested by submerging 1 m² ofthe substrates shown in FIG. 1.7 in the southern (off the Chilean coast)and northern (off the Canadian coast) hemispheres to account forseasonal variations in aquaculture environments. The substrates wereexamined after 30 and 60 days of testing. The substrates that werecoated with polymer 2b were effective at preventing bacteria adsorptionon the polymer substrates. After 30 days, the uncoated samples werecompletely covered with bacteria, algae, barnacles, and other seacreatures, while the substrates coated with polymer 2b were free offouling, except for a thin film of dead bacteria. After 60 days, the 2bcoated substrates had succumbed to bacterial adsorption because ofbiofouling on the dead bacteria surface. This coating of bacteria andalgae was easily wiped away, while the fouled, uncoated substrates, werevery difficult to clean by hand, and required excessive pressure washingwith a stream of high pressure water.

Example III

Additional Polymer Structures to Add Vinyl Functional Groups to theSurface Using Photocrosslinking Polymers.

Linear Copolymer of N,N-undecene methyl andN,N-[(6-hexyl)oxy]benzophenone methyl PEI:

0.25 g (6 mmol of the monomer unit) of the PEI was dissolved in 6 mL oftert-amyl alcohol, followed by the addition of 1 g (7 mmol) of K₂CO₃,1.17 g (5 mmol) of 11-bromo-1-undecene, and 0.36 g of4-[(6-bromohexyl)oxy]benzophenone and the reaction mixture was stirredat 95° C. for 96 h. After removing the solids by filtration underreduced pressure, 1 mL of iodomethane was added, followed by string at60° C. for 24 h in a sealed fluxed. The solution was dried under rotaryevaporator. The yellow solid was dissolve in minimum volume ofdichloromethane and then added excess hexane to precipitate the polymer.Light yellow solid was filtered and dried at room temperature undervacuum for overnight. Yield: 1 g (44%).

Functionalization of PEI Polymer on Other Polymer Surface:

15 mg of quaternized polymer was dissolved in 1 mL of acetone solvent.The solution was filtered through 0.25 μm filter. The polymer film wasdeveloped on Hytrel-4056 or Petrothene polymer surface by spin coatingwith 0.5 mL of solution at 1000 rpm. The polymers were radiated with UVlight (360 nm, 180 mW/cm²) for 30 mins to covalently bound the PEIcopolymer on other polymer surfaces with benzophenone as linker. Thesubstrate was sonicated with acetone (for Hytrel-4056) oracetone/methanol (30:70) mixture (for Petrothene) for one minute anddried under air.

Result and Discussions:

We have synthesized quaternary amine polymer with a attachment ofbenzophenone moiety. The polymer was prepared by reacting PEI polymerwith 4-[(6-Bromohexyl)oxy]benzophenone and 11-bromo-1-undecene. Thepolymer was characterized by both NMR and IR to confirmed the presenceof benzophenone and undecene moieties. The polymer is soluble inhalogenated solvents and acetone and slightly soluble in methanol orethanol. Our strategy is to photochemically attach the polymer materialonto the surface using the benzophenone (BP) moiety as a cross-linker,as described herein.

In the present example we use two different polymer surfaces,Hytrel-4056 and Petrothene for surface coating purposes. Hytrel-4056 isa polyester and petrothene is a linear polyethylene. The surfaceattachment of the PEI copolymer was investigated by FTIR. FIG. 2.1 showsthe FTIR spectra of Hytrel-4056, PEI functionalized Hytrel-4056, and thespectrum for the PEI copolymer. FTIR clearly indicates that the coatedHytrel sample (bottom graph, FIG. 2.1) has all characteristic peaks forHytrel polymer as well as PEI copolymer except for the C═O absorbancepeak at 1735 cm⁻¹, which is from the benzophenone unit in the PEIcopolymer. The disappearance of this peak upon crosslinking indicatescovalent attachment between the two polymers. Also the coated sample hasa weak absorption peak at 3078 cm⁻¹ corresponding to C═C—H stretchingmode, which is an indication that the vinyl functionality is retained inthe sample after crosslinking.

FIG. 2.2 shows the IR spectra of PEI copolymer, Petrothene coated withPEI copolymer and Petrothene. The Petrothene sample (bottom) has nosignificant absorption between 1600 cm⁻¹ to 1000 cm⁻¹ where as PEIpolymer coated petrothene (middle) show several absorptions due to thePEI containing copolymer in this region. IR data confirmed the covalentattachment of PEI copolymer onto the petrothene surface through thedisappearance of the C═O stretching peak at 1735 cm⁻¹ as indicatedabove.

Example IV

The attachment of functionalized diaryl(or alkylaryl) ketones tosurfaces can be achieved using active C—H bonds in the substrate (toundergo insertion of the keto group), and the selection of theappropriate wavelength of the UV incident radiation such as to promotehomolysis of the keto group π bond. Consequently, myriad surfaces arepotentially suitable to undergo irreversible attachment offunctionalized ketones, which in turn will enable the development ofmultiple surface modifications and coatings of industrial importance.

In an embodiment, materials having the either of the following chemicalstructures can be used to attached to one or more surfaces.

Q is a photo cross-linkable moiety such as those described above inreference to B. In an embodiment, Q can be attached to two “X—R-vinylgroup” groups, where the “X—R-vinyl group” are the same or different. Xcan include C, O, N, B, S, Al, Si, P, or Sn, where one or moreadditional moieties (e.g., a second vinyl group (e.g., R-vinyl group),H, an alkyl group, and the like (e.g., X can be CH₂)) can be attached toX as needed (e.g., to satisfy atom's normal valence). R can include asubstituted or unsubstituted alkyl, substituted or unsubstituted aryl,substituted or unsubstituted cycloalkyl, substituted or unsubstitutedcycloalkenyl, substituted or unsubstituted aryl, substituted orunsubstituted biaryl, substituted or unsubstituted fused aryl,substituted or unsubstituted alkenyl, and substituted or unsubstitutedalkynyl, combinations of each, and the like. Semicircle P can include apolymer, compound, and the like, where multiple photo cross-linkablemoiety and/or vinyl groups can be included.

In an alternative embodiment, the —(HC═CH₂) terminal group connected toR, can actually be other groups, such as substituted alkenes such as inacrylic acid fragment (CH₂CH₂CO(OH)), esters of acrylic acid (e.g.,methyl acrylate that would lead to PMMA attached to the first surface),amine or diamine (which could lead to polyamide or such as nylon, oraramid by reaction with lactams or diacyl and diamine),alcohol/diol/polyols (e.g., —CH(OH)—CH₂—CH(OH)—CH(OH)—CH₃), which canlead to polyesters through reaction with diacids and diols) and diacids(e.g., HOC(O)—CH₂—CH₂—C(O)OH).

In an embodiment, the material can include either of the followingchemical structures can be used to attached to one or more surfaces.

In addition, three exemplar types of materials (A through C shown belowin Example IV) that can be used to modify the properties of Hytrel andpoly(ethylene) [used herein as model substrates] that will provideterminal double bonds to the surface of the polymers for furthergrafting are herein described. These modifications will be applied tocommercial items made of PE and/or Hytrel, along with any othernecessary polymers for surface grafting, for further modification of thetethered units. In this example, “vinyl” may refer to the —CHCH₂ moietyconnected through an alkyl spacer (and or a heteroatom) to an aromaticketone.

A. Small Molecule Synthesis of Vinyl Benzophenone Materials that can beDirectly Grafted Using Mild UV Light.

Example 1—Monosubstituted, Alkoxy-Linked Benzophenone Containing aLinear —OC₆H₁₂ Spacer Between the Vinyl Functionality and theBenzophenone Moiety

Above is the structure of the benzophenone used as model for surfacemodification for the addition of tethered HC═CH₂ functionality onto asurface. The alkyl spacer linker between terminal vinyl group and BP canbe varied between C6-C18. Surface characterization of the functionalizedpolymers can be performed using attenuated total reflection spectroscopyand surface force/tension measurements.

The above substituted benzophenone can be reacted with the surface of afirst polymer substrate (e.g., PMMA), in the presence of UV light, toyield a modified first surface containing multiple covalently bound—O—C(H)(C₆H₅)(C₆H₄—C₆H₁₂—CH═CH₂) moieties, in which the tethered vinylgroups can then be either polymerized, blended, and crosslinked throughradical or cross-metathesis chemistry or other carbon-carbon bondforming reactions, to yield a polymer cross-linked by covalent C—Cbonds.

The above substituted benzophenone can be reacted with the surface of afirst polymer substrate (e.g., PMMA), in the presence of UV light, toyield a modified first surface containing multiple covalently bound—O—C(H)(C₆H₅)(C₆H₄—C₆H₁₂—CH═CH₂) moieties, in which the tethered vinylgroups can then be polymerized (e.g., directly or through reaction withethylene) to yield a first polymer surface coated by a covalently boundmonolayer of PE (See FIG. 5.1). This yields a first surface (e.g., PMMA)modified by a monolayer of a second surface (e.g., PE) in which thefirst and second surfaces are covalently bound to each other bydiphenylmethoxy groups.

B. Polymer Backbone Modification.

Polymethacrylates with different compositions of vinyl monomers and BPside chains can be copolymerized for further grafting of polymers. Thebenzophenone moiety is used to conduct the light-promoted attachment toa first surface, while tethered vinyl group is used for further graftingof a polymer (that constitutes the second surface) bound to the firstsurface (x and y are independently about 1 to 50 or 1 to 20). Thesemonomers can be copolymerized by both radical, controlled radical, andother polymerization methodologies.

C. Silicone Backbone Modification

Hydrosilization reactions can be used to generate surface attachablesiloxanes used to modify silicone backbones. Further grafting to yieldthe second surface or crosslinking can be done through the same methodas described in B.

It will be recognized that in addition to the aromatic ketones of Athrough C, other variants of such ketones may be employed, under similarconditions, to yield similar results. Examples of ketones that may beused in the reaction schemes under A-C, and in place of the ketonesdescribed therein are described in Examples 2-5 below. Such ketoneswould provide a framework for a three-dimensional second surfacecomprised of, for instance, cross-linked PE. Additionally, thioketones(RR′C═S) are also capable of providing a way of attachment of a secondsurface onto a first surface, by the methods described herein.

It will also be recognized that the linkage of the [alkyl spacer-vinyl]unit (R′) to the aromatic ketone group may be accomplished through meansother than through C, O, N, illustrated in examples 1-5. For instance,and without intending to be limiting, —SR′, —SnR′₃, [Fe(Cp-R)₂]⁺, NR′₃⁺, cyclic —C₆H₆R′₆, may be used to link multiple R′ units to a singleketone group.

It will be further recognized that the embodiments of the presentdisclosure are not limited to the use of benzophenone.Alkyl-arylketones, as well as diarylketones bearing at least onecondensed ring system substituent such as naphtyl and anthracenyl, mayalso be employed and their attachment to the original surface may bepromoted by simple choice of a UV radiation of suitable wavelength.

Example 2—Monosubstituted Benzophenone Bearing Multiple Vinyl Groups[1≦n≦18]

Example 3—Disubstituted Benzophenone Bearing Multiple Vinyl Groups[1≦n≦18]

Example 4—Mono(divinylamino)-Substituted Benzophenone Bearing MultipleVinyl Groups [1≦n≦18]

Example 5—Bis(divinylamino)-Substituted Benzophenone Bearing MultipleVinyl Groups [1≦n≦18]

Example 5 is a prototypical example of heteroatom linkage to thearomatic ketone. It is further recognized that C, O, B, S, Al, Si, P,Sn, may replace N to yield novel benzophenone structures and that highlyderivatized, organic (e.g., pentaallyl-substituded cyclohexyl) andorganometallic fragments (e.g., allyl-substituted ferocenyl,vinyl-substituted chromocene and metallo-carbonyl derivatives) may alsobe linked to the aromatic ketone moiety. It is noted that thesesubstitutions can alter the wavelength of light needed to excite theradical coupling reaction.

It will further be recognized that the embodiments of the presentdisclosure are not limited to the attachment of a PE-based secondsurface to an original surface or crosslinking reactions. Through theappropriate choice of a terminus for the tethered group, such terminusbeing a monomer of a polymer or a monomer for a copolymer, the secondsurface or cross-linking matrix may be comprised of different polymers.For instance, an acrylate group to yield a polyacrylate second surfaceor cross-linked matrix; an organic diacid to yield a polyester-basedsecond surface or cross-linked matrix through reaction with a diol; adiacylchloride to yield a polyamide (or aramid)-based second surface orcross-linked matrix through reaction with an appropriate diamine;trifluorovinyl to yield a poly-trifluoroethylene second surface; analkyne terminus to yield a polyacetylene-based second surface.

Such modifications can lead to modifications of properties of articlesof polymers constituents of the first surface. For instance, articlesmade of a mechanically strong, but hydrophilic, material may be madehydrophobic by the modification herein, through the appropriate designof a tethered group that can be used for grafting of a hydrophobicpolymer.

The substrate (first surface) can be any surface with C—H bonds that arereactive through the process described herein. Examples include, withoutlimitation, materials such as keratin, polyethylene, cellulose,acrylics, pectin, lignin, chitin, PVC, among others, as well as othersdescribed herein.

Example V

Brief Introduction:

Antimicrobial copolymers of hydrophobic N-alkyl and benzophenonecontaining polyethylenimines were synthesized from commerciallyavailable linear poly(2-ethyl-2-oxazoline), and covalently attached tosurfaces of synthetic polymers, cotton, and modified silicon oxide usingmild photocrosslinking. Specifically, these polymers were applied topolypropylene, poly(vinyl chloride), polyethylene, cotton, and alkylcoated oxide surfaces using solution casting or spray coating and thencovalently crosslinked rendering permanent, nonleaching antimicrobialsurfaces. The photochemical grafting of pendant benzophenones allowsimmobilization to any surface that contains a C—H bond. Incubating themodified materials with either Staphylococcus aureus or Escherichia colidemonstrated that the modified surfaces had substantial antimicrobialcapacity against both Gram-positive and Gram-negative bacteria (>98%microbial death).

Introduction:

Microbial infection is one of the most serious concerns for manycommercial applications such as textiles, food packaging and storage,shoe industry, water purification, medical devices, and dental surgeryequipment.¹⁻⁴ Recently, antimicrobial agents have gained significantinterest from both an academic and industrial point of view because oftheir potential to provide safety benefits to a diverse range ofmaterials. Some cationic polymers, like quaternary polyetheleneimines(QPEIs), have proven effective at killing bacteria because of theirunique structural and hydrophobic properties.⁵⁻¹⁰ The generally acceptedhypothesis for antimicrobial activity of polycations with hydrophobicside chains is that the pendant hydrophobic groups can intercalate intothe hydrophobic portion of a cell membrane, while the electrostaticinteraction of the positively charged backbone and the negativelycharged bacterial cell membrane/wall disrupts the ionic integrity of themembrane, causing cell death.¹¹⁻¹⁵ However, a more detailed mechanismfor rapid contact kill of bacteria at the solid surface interfaceremains an important unexplored research area. To achieve this goal, thedevelopment of a new methodology for surface immobilization ofantimicrobial polymers with well-defined properties is necessary. It isalso of great interest to obtain biocidal effects without releasingbiocide material into the environment, which means that antimicrobialcoatings need to be immobilized irreversibly or covalently attached tosurfaces. A significant number of literature reports discuss thepreparation of antimicrobial surfaces via the covalent coupling of polyquaternary ammonium (PQA) compounds to a variety of surfaces likeglass,¹⁶⁻¹⁸ polymer,¹⁹⁻²⁵ paper,²⁶ and metal.²⁷ Recently, Hsu andKlibanov²⁸ reported a system in which an aryl azide based biocidal PEIcopolymer was used to modify cotton fabrics. In this case, thenitrophenylazide based crosslinker reacts preferentially with thehydroxy functionality on the cellulose surface. While this methodologyis achievable with surfaces that contain reactive functional groups(examples include hydroxy, amine, carboxylic acid, and chloro), thecovalent attachment of biocidal polymers on common and inert plasticsurfaces such as polyethylene, polypropylene, and polystyrene is morechallenging with very few examples in the literature.²⁹⁻³²

The ability of benzophenone (BP) to act as a cross-linking agent andabstract hydrogen from a suitable hydrogen donor has been well studiedand utilized in various chemical systems for many years.³³⁻³⁹ BP is anideal choice for crosslinking organic thin films, because it can beactivated using mild UV light (345-365 nm), avoiding oxidative damage ofthe polymer and substrate that can occur upon exposure to higher energyUV. The benzophenone moiety is more chemically robust than other organiccrosslinkers and reacts preferentially with C—H bonds in a wide range ofdifferent chemical environments. Triggered by UV light, benzophenoneundergoes an n-π* transition, resulting in the formation of a biradicaltriplet excited state that can abstract a hydrogen atom from aneighboring aliphatic C—H group to form a new C—C bond.⁴⁰ Thisphotoreaction has recently been used to attach thin polymer layers tometal and oxide surfaces,⁴¹⁻⁴⁶ along with applications inmicrofluidics,⁴⁷ organic semiconductors,⁴⁸ redox polymers,^(49,50) andbiosensors.⁵¹

In this article we describe a convenient method to covalently attachultrathin biocidal polymer coatings on surfaces with inertfunctionality. We have synthesized antimicrobial copolymers with pendantbenzophenone groups that act as a photo-crosslinker for the covalentattachment of the polymer with any substrate containing a C—H bond uponirradiation with UV light. The coated substrates showed impressiveantibacterial and antifouling properties. To our knowledge, this is thefirst demonstration for the covalent immobilization of antimicrobialpolymers onto inert polymer surfaces.

Experimental

Materials:

Silicon wafers (Universitywafer.com) with native oxide and glass slides(VWR) (cut into 2.5×2.5 cm pieces) were used as substrates.Poly(2-ethyl-2-oxazoline) (Aldrich), tert-amylalcohol (Aldrich),1-bromododecane (Alfa Aesar), iodomethane (Alfa Aesar),4-hydroxybenzophenone (Alfa Aesar), 1, 6-dibromohexane (Alfa Aesar),trypticase soy broth (TSB) (Difco), trypticase soy agar (TSA) (Difco),were used as received.

Instrumental Methods:

Atomic force microscopy (AFM) experiments for quaternized PEI basedpolymer films were performed using a Multimode Nanoscope IIIa (DigitalInstruments/Veeco Metrology Group). All measurements were performedusing tapping mode. Null ellipsometry was performed on a Multiskop(Optrel GbR) with a 632.8 nm He—Ne laser beam as the light source. Bothδ and ψ values were measured and thickness was calculated by integratedspecialized software. At least three measurements were taken for everylayer, and the average thickness was calculated. UV-vis spectroscopy wasperformed on a Cary 50 spectrophotometer (Varian). Infrared spectroscopystudies of polymer coated films were done using a Thermo-Nicolet Model6700 spectrometer equipped with a variable angle grazing angleattenuated total reflection (GATR-ATR) accessory (Harrick Scientific).The UV light source was an OmniCure, Series 1000 with 365 nm bandpassfilter, equipped with a liquid filled fiber optic waveguide. Thesubstrates were held 2 cm from the source and irradiated with a power of180 mW/cm².

Antimibacterial Test Method:

Trypticase soy broth (TSB) (10 ml) was inoculated with one loopful ofbacteria Staphylococcus aureus (ATCC 6538) culture or Escherichia coli(ATCC 25922) and incubated overnight in a water shaker bath at 37° C.with 45 linear strokes per minute (TSB contains 17 g of casein peptone,3 g of soy meal peptone, 2.5 g of D-(+) glucose, 5 g of NaCl and 2.5 gof dipotassium hydrogen phosphate per liter). The new TSB (10 ml) wasagain inoculated with 100 μl of an overnight bacterial culture andincubated for 4 hours in the above-mentioned conditions in the shakerbath. One milliliter of this culture was transferred to a 1.5 mLcentrifuge tube and was centrifuged at 5000 rpm for 1 minute at 21° C.to precipitate bacteria and form a bacterial pellet.(Centrifuge=accuSpin Micro 17R, Fisher Scientific, Tubes=MicroCentrifuge Tube, VWR International). The supernatant solution wasdiscarded and 1 mL of sterile water was added to the microbial pellet inthe tube. The microbes were re-suspended in the solution by using avortex mixer (Vortex Genie 2) and was transferred to 9 mL of sterilewater to make a bacterial concentration of ˜3×10⁶ cfu (colony formingunits) and subsequently transferred to thin layer chromatography (TLC)sprayer bottle which was connected to pneumatic dispense regulator (EFD1500XL). The polymer coated substrates were uniformly sprayed on oneside in a controlled fashion from the TLC sprayer for 1 second at 30-40psi pressure. The distance between the sprayer and glass slide wasapproximately 1½ feet. The sprayed sample was air dried forapproximately 1 minute and the sample was carefully mounted on a Difco™Trypticase soy agar (TSA) plate (TSA contains 15.0 g of pancreaticdigest of casein, 5.0 g of enzymatic digest of soybean meal, 5.0 g ofsodium chloride, and 15.0 g of agar per liter). TSA plates wereincubated for 24 hours at 37° C. Finally, the number of colonies grownon the slide was counted.

Synthesis

Linear Polyethylenimine (PEI):

The deacylation reaction was performed according to literatureprocedures.⁵² 3 g of poly (2-ethyl-2-oxazoline, M_(w), 50 kDa) (POEZ)was added to 120 mL of 24% (wt/vol) HCl, followed by refluxing for 96 h.The POEZ dissolved completely in 1 h, but after overnight reflux a whiteprecipitate appeared. The precipitate was filtered and then air-dried.The resultant protonated, linear PEI was dissolved in water andneutralized with aqueous KOH to precipitate the polymer. The whitepowder was isolated by filtration, washed with distilled water until thepH became neutral, and dried under vacuum. Yield: 1.15 g (88%). ¹H NMR(CDCl₃): δ, 2.72 (s, 4H, NCH₂CH₂N), 1.71 (1H, NH).

4-[(6-Bromohexyl)oxy]benzophenone

4-Hydroxy benzophenone (5.94 g, 30 mmol), 1,6 dibromohexane (8.05 g, 33mmol), potassium carbonate (5.95 g, 45 mmol) and DMF (60 mL) werestirred at room temperature for 16 h under inert atmosphere. Thereaction mixture was poured into ice water (300 mL) and extracted withether (100 mL). The organic layer was collected and the solvent wasremoved with a rotary evaporator. The crude product was purified on asilica gel column by using 10:1 hexane:ethyl acetate mixture. Yield: 8.2g (76%). ¹H NMR (CDCl₃): δ, 7.81 (d, 2H, J=8.4 Hz), 7.75 (d, 2H, J=7.8Hz), 7.54 (t, 1H, 7.5 Hz), 7.47 (t, 2H, J=6.9 Hz), 6.93 (d, 2H, J=9.0Hz), 4.06 (t, 2H, J=6.3 Hz), 3.43 (t, 2H, 6.6 Hz), 1.86 (m, 4H), 1.50(m, 4H). ¹³C NMR (CDCl₃): δ, 25.47, 28.10, 29.11, 32.86, 33.95, 68.2,114.2, 128.37, 129.92, 129.94, 132.06, 132.78, 138.55, 162.9, 195.7.

Linear Copolymer of N,N-dodecyl methyl andN,N-[(6-hexyl)oxy]benzophenone methyl PEI:

0.5 g (12 mmol of the monomer unit) of the PEI was dissolved in 6 mL oftert-amyl alcohol, followed by the addition of 2.1 g (15 mmol) of K₂CO₃,1.99 g (8 mmol) of 1-bromododecane, and 1.44 g (4 mmol) of4-[(6-bromohexyl)oxy]benzophenone and the reaction mixture was stirredat 95° C. for 96 h. After removing the solids by filtration underreduced pressure, 1.5 mL of iodomethane was added, followed by stirringat 60° C. for 24 h in a sealed, heavy walled pressure vessel. Afterreaction, the solution was dried using a rotary evaporator. The yellowsolid was dissolved in a minimum volume of dichloromethane and then thesolution was added to excess hexane to precipitate the polymer. Thelight yellow solid was filtered and dried at room temperature undervacuum for 12 hours. Yield: 2.3 g (46%). ¹H NMR (CDCl₃): δ, 7.77 (bs,4H); 7.56 (bs, 1H), 7.45 (bs, 2H); 6.96 (bs, 2H); 4.19-3.26 (m, 21H);1.83 (bs, 6H); 1.65 (bs, 16H); 1.23 (bs, 34H), 0.87 (bs, 6H). ¹³C NMR(CDCl₃): δ, 195.73, 162.88, 138.24, 132.56, 131.72, 129.71, 128.25,114.32, 67.95, bs 53.45, 31.90, 29.65, 29.59, 29.53, 29.47, 29.36,22.67, 14.11.

Preparation of Self-Assembled Monolayers on Glass Substrates:

Glass slides were cut into rectangles. The substrates were sonicatedwith Fisherbrand sonicating soap, 18.2 MΩ deionized water, isopropanol,and acetone for 10 min each and finally dried in an oven for 1 h. Aftercleaning, a self-assembled monolayer (SAM) of octyltrichlorosilane wasformed from the vapor phase by suspending the substrates in a vacuumdesiccator and placing two drops of silane on a glass substrate at thebottom. The substrates were kept in a vacuum flux (constant pressure of100 millitorr) for 20 min. After venting with nitrogen, the substrateswere sonicated with acetone and dried under air.

Surface Bound PEI Polymer (2):

15 mg of quaternized polymer (2) was dissolved in 1 mL of acetonesolvent. The solution was filtered through 0.25 μm filter. The polymerfilm was developed on functionalized glass substrate by spin coatingwith 0.5 mL of solution at 1000 rpm. The glass substrate was irradiatedwith UV light (365 nm, 180 mW/cm²) for 15 mins to covalently bind thepolymer on the glass surface through the pendant benzophenone moiety.The substrate was sonicated with acetone for one minute and dried underair.

Result and Discussions:

Copolymer 2, which contains both hydrophobic and benzophenone sidechains, was prepared by reacting linear PEI with4-[(6-Bromohexyloxy)]benzophenone and 1-bromododecane (Scheme 1) alongwith subsequent quaternization using iodomethane. The copolymercomposition was checked by NMR spectroscopy, which revealed that thepolymer composition matched the pendant group feed ratio. Copolymer 2 issoluble in halogenated solvents, acetone, and slightly soluble inalcohols. As described above, the benzophenone component of 2 can act asa cross-linker between the hydrophobic PEI polymer and any organicsubstrate through C—H activation. Initially, we have used glass andsilicon wafers functionalized with alkyl SAMs to analyze the polymerfilm thickness before and after crosslinking, kinetics offunctionalization, and to observe any surface morphology changes throughatomic force microscopy. Flat substrates also simplify the antimicrobialactivity assays because of the ease of analytical quantification.

The cross-linking and structure of the covalently bound polymer surfacesis shown in Scheme 7 (other types of polymer of the present disclosurecan be used in place of the one shown in Scheme 7). Initially, the oxidesurfaces were functionalized with octyltrichlorosilane (OTS) to generateC—H alkyl groups on the surface. To this modified surface a thin layerof polymer 2 was deposited using spin coating (15 mg/mL in acetone, 1000rpm). Covalent attachment was generated by exposure to UV irradiation(365 nm, 180 mW/cm²) for 15 minutes. The crosslinked films were thenwashed with acetone and sonicated in acetone for one minute to removeany residual, unbound materials. The polymer film thickness was measuredbefore and after sonication and was observed to be 93 and 77 nmrespectively, indicating that approximately 80% of the coating remainedafter cross-linking. The thickness of the cross-linked coating did notchange upon prolonged sonication in any organic solvent.

The kinetics of surface attachment of copolymer 2 was investigated byUV-vis spectroscopy on OTS functionalized quartz substrates. Timedependent changes in the absorption spectra of the film under UV lightirradiation are shown in FIG. 1.1.⁵³ Photon absorption at 365 nm resultsin the promotion of one electron from a nonbonding n-orbital to anantibonding π*-orbital of the carbonyl group on the benzophenone moiety.The n-π* transition yields a biradicaloid triplet state where theelectron-deficient oxygen n-orbital is electrophilic and thereforeinteracts with weak C—H δ-bonds, resulting in hydrogen abstraction tocomplete the half-filled n-orbital.^(54,55) The two resulting radicalspecies can then combine to form a new C—C bond. The reaction progresscan be monitored indirectly by following the decrease in the π-π*transition of benzophenone at 290 nm. As expected, this peak decreaseswith increasing irradiation time. After ˜30 minutes, the reaction iscomplete as observed, with no further changes in the spectrum withprolonged irradiation.

The photochemical attachment of copolymer 2 was also confirmed usinggrazing incidence attenuated total internal reflection fourier transforminfrared spectroscopy (GATR-FTIR). Copolymer 2 was spincast onto asilicon wafer that was modified with a SAM of OTS. FIG. 3.1 shows theGATR-IR spectrum of a silicon wafer modified with copolymer 2 (A) beforeand (B) after UV irradiation. In FIG. 3.1, spectra A, the peaks at 2920and 2849 cm⁻¹ are due to C—H stretching of the aliphitac backbone andpendant groups. The C═O of the benzophenone pendant group is observed at1648 cm⁻¹. The C—C ring vibrations are assigned at 1600 cm⁻¹ along withthe C—N⁺ stretch at 1468 cm⁻¹. Peaks at 1253 and 1020 cm⁻¹ are assignedto the C—O—C asymmetric and symmetric stretches respectively. FIG. 3.1,spectra B shows the polymer film after irradiation. A significantreduction in the C═O stretch at 1648 cm⁻¹ is readily apparent, whichindicates photo-decomposition of the carbonyl group along with thecovalent attachment of 2 onto the OTS functionalized SiO₂ surface. Theoverall decrease in all peak intensities correlates with the decrease infilm thickness after crosslinking and subsequent sonication.

AFM was used to characterize the surface morphology of copolymer (2)film before and after sonication to remove any non-covalently boundpolymer from the surface. Before and after sonication, the irradiatedfilm of 2 was very smooth. A representative morphology for both is shownin FIGS. 1.2 and 1.3. The thickness of the film is 93 nm (measured withellipsometry) with an RMS roughness 0.48 nm by AFM. FIG. 1.3 shows themorphology of the film after sonication. The overall film thicknessdecreased to 77 nm after sonication, with an increase in surfaceroughness to 0.83 nm due to removal of non-covalently attached polymerfrom the surface.

The effectiveness of the polymer-coated surfaces to kill bacteria wastested on different plastics, fabrics and alkyl functionalized glasssubstrates. For covalently bonded biocides, direct contact of theorganism with the antimicrobial moiety is required for the antibacterialactivity.^(56,57) In these experiments, microbes were uniformly sprayedon the polymer coated surfaces using a TLC sprayer connected topneumatic dispense regulator. The sprayed sample was air dried andmounted on a TSA plate which was incubated for 24 hours at 37° C. Thenumber of colonies grown on the slide was then counted by visualizationunder an optical microscope. To examine the influence of polymer coatingthickness on the biocidal activity, copolymer 2 was spin-cast onto flatsubstrates using solutions of different concentration. This alloweduniform, reproducible thickness that varied between 30-93 nm afterirradiation and sonication. The thickness of the coating had an impacton the biocidal activity (Table 1). The surface grafted with a highdensity of polymers exhibited relatively high biocidal activity. Whenthe thickness of the polymer layer is greater than 50 nm, the coatingwas >99% effective and all bacterial colonies were killed. FIGS. 3.2A-Bshow the digital photograph of the control and polymer functionalizedsurfaces after spraying with S. aureus and incubated for 24 hours at 37°C. As seen in FIG. 3.2A, numerous colonies of S. aureus are grown on thecontrol slide after spraying the bacterial suspension onto the surface.On the other hand, a bacterial reduction greater than 99% is observed onthe same substrate coated with copolymer 2 (FIG. 3.2B).

TABLE 1 Example V. Antimicrobial test with S. aureus along with percentbacterial reduction. There were four sets of samples tested: (1) Controlglass substrate with OTS coated SAM, (2) spin coated glass substratewith 5 mg/mL polymer concentration, (3) spin coated glass substrate with10 mg/mL polymer, and (4) spin coated glass substrate with 15 mg/mLconcentration. The copolymer (2) was spin coated on the glass sample andirradiated with UV light (365 nm, 180 mW/cm²) for 15 minutes andsonicated in acetone for 1 minute. The coated and control samples weresprayed with S. aureus solution and incubated for 24 hours at 37° C. 5mg/ml polymer 10 mg/ml polymer 15 mg/ml polymer Control conc. conc.conc. (CFU) SUV* SUVS* SUV SUVS SUV SUVS Uncoated Film Film Film FilmFilm Film glass Thickness Thickness Thickness Thickness ThicknessThickness slides 35 nm 31 nm 55 nm 53 nm 93 nm 77 nm 1 258 1 15 0 3 0 42 247 4 16 0 4 0 2 3 158 0 10 0 3 3 2 Average 221 1.66 13.66 0 3.33 12.66 % — 99.24 93.81 100 98.49 99.54 98.79 Reduction *SUV = Spin-coatedUV radiated unsonicated glass slides *SUVS = Spin-coated UV radiatedsonicated glass slides

TABLE 2 Example 5. Antimicrobial test with E. coli along with percentbacterial reduction. There were four sets of samples tested: (1) Controlglass substrate with OTS coated SAM, (2) spin coated glass substratewith 5 mg/mL polymer concentration, (3) spin coated glass substrate with10 mg/mL polymer, and (4) spin coated glass substrate with 15 mg/mLconcentration. The copolymer (2) was spin coated on the glass sample andirradiated with UV light (365 nm, 180 mW/cm²) for 15 minutes andsonicated in acetone for 1 minute. The coated and control samples weresprayed with S. aureus solution and incubated for 24 hours at 37° C. 5mg/ml polymer 10 mg/ml polymer 15 mg/ml polymer Control conc. conc.conc. (CFU) SUV* SUVS* SUV SUVS SUV SUVS Uncoated Film Film Film FilmFilm Film glass Thickness Thickness Thickness Thickness ThicknessThickness slides 35 nm 31 nm 55 nm 53 nm 93 nm 77 nm 1 91 0 11 1 0 0 1 281 2 24 0 11 0 0 3 136 2 26 0 6 0 1 Average 102.66 1.33 20.33 0.33 5.660 0.66 % — 98.70 80.19 99.67 94.48 100 99.35 Reduction *SUV =Spin-coated UV radiated unsonicated glass slides *SUVS = Spin-coated UVradiated sonicated glass slides

To establish the generality of the effectiveness of our polymercoatings, we also tested against the human pathogenic bacteriumEscherichia coli (E. coli, which is a Gram-negative bacterium). Theresults of which are shown in Table 2. As also seen in FIGS. 3.3A-B, thepolymer-coated slides once again afforded a 99% killing efficiencyagainst E. coli.

In order to investigate the versatility of these copolymers on commodityplastics and textile fabrics, variety of substrates such as cotton,polypropylene, polyethylene and poly(vinyl chloride) werephotochemically modified with copolymer 2 using simple spray coatingtechnique. The copolymer, dissolved in acetone, was uniformly sprayedcoated with a laboratory TLC sprayer. The substrates were air dried andirradiated (365 nm, 180 mW/cm²) to covalently attach the polymer to theplastic surface. After UV curing, the substrates were thoroughly washedin acetone to remove any non-covalently attached copolymer. Thecopolymer treated and untreated fabrics were challenged against S.aureus with the antibacterial test method described earlier. FIGS.3.4A-H show bacterial proliferation on the untreated fabrics andexcellent antibacterial activity on the treated fabrics. The resultsdemonstrate covalent immobilization of polymer 2 on all substrates,including those with reactive functional groups such as cotton as wellas on inert plastic surfaces such as polypropylene, poly(vinyl chloride)and polyethylene.

Conclusions:

In this Example, we have demonstrated a novel and efficient approach tocovalently attach antimicrobial polymer on any substrate with a C—Hbond. A hydrophobic PEI copolymer substituted with benzophenone sidechain (2) was spin-casted or spray-coated on a wide range of surfacesfrom cotton to inert plastics and photo-crosslinked by UV irradiation.After the covalent attachment of polymer on the surface, the biocidalactivity was investigated against both Gram-positive (S. aureus) andGram-negative (E. coli) bacteria. The surface grafted with a highdensity of polymers exhibited relatively high biocidal activity. Whenthe thickness of the polymer layer was greater than 50 nm, essentiallyalmost all the bacteria were killed. This one step photochemicalattachment process of an ultrathin antimicrobial coating is both simpleand scalable for industrial applications.

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Example VI Experimental

Materials: Ethylene-methyl acrylate copolymer (Optema TC 115), lowdensity polyethylene (LDPE) (SABIC 2100), ethyl vinyl acetate (EVA)(Elvax® 460), 4-hydroxybenzophenone (TCI), 11-bromo-1-undecene(Sigma-Aldrich) were used as received.

Instrumentation:

The coated substrates were dissolved in deuterated benzene for protonNMR analysis and spectra were recorded using a Varian Mercury 500 NMRspectrometer working at 500 MHz. An internal standard oftetramethylsilane was used to report relative chemical shifts.

Synthesis:

The reaction mixture of 4-hydroxybenzophenone (0.99 g, 5 mmole),11-bromo-1-undecene (1.16 g, 5 mmole), K₂CO₃ and n,n-dimethylformamide(DMF) (20 ml) was stirred at room temperature for 16 hours under inertatmosphere. The reaction mixture was poured into ice water (100 ml) andextracted with ether (3×20 ml). The organic layer was collected, and thesolvent was removed by rotary evaporator. The crude product was purifiedon silica gel column by using 10:1 hexane/ethyl acetate mixture. ¹H NMR300 MHz, (CDCl₃): δ, 7.81 (d, 2H, J=6.3 Hz), 7.76 (d, 2H, J=7.2 Hz),7.56 (d, 1H, J=7.3 Hz), 7.46 (t, 2H, J=8.7 Hz), 6.94 (d, 2H, J=8.4 Hz),5.88 (m, 1H), 4.91 (m, 2H), 4.04 (t, 2H, J=7.7 Hz), 2.2 (q, 2H), 1.81(p, 2H), 1.31 (m, 12H).

Coating Procedure:

The polymer substrates (provided in powder form ground from pellets)were coated with BP1 using different concentrations of coatingsolutions. The modified BP was dissolved in acetone and spray/slurrycoated on the substrates. Upon air drying, the substrates wereirradiated with mild UV to attach the coating onto the substratesurface. The coating to substrate ratio was varied from 33:100 to 5:100.The coated substrate was washed with acetone to remove any nonbonded,physisorbed BP1 material.

FIGS. 4.1 and 4.2 shows the proton NMR spectra of copolymer coated withdifferent concentration of BP1. Both the spectra clearly showed surfacemodification of given copolymer. Aromatic protons (7.47, 7.37, 6.32ppm), vinyl protons (5.4 and 4.62 ppm) and protons from ether linkage(3.16 ppm) of coating were observed. The given ethylene-methyl acrylatecopolymer contains 12% methyl acrylate polymer component. The amount ofmodified benzophenone coating was calculated based on the assumption of12% acrylate content. The peak integration calculations showed that inthe case of coating and copolymer ratio of 33:100, there wasapproximately 6.52% coating (based on ether linkage of BP1) and 5.12%coating (based on the aromatic protons from BP1) was left on the surface(FIG. 4.1). In the case of coating and copolymer ratio of 5:100, therewas approximately 1.56% coating (based on ether linkage of BP1) and0.96% coating (based on the aromatic protons from BP1) was left on thesurface (FIG. 4,2) after rinsing away physisorbed materials.

The coating procedure was repeated on other polymers with a differentchemical nature. The polymers namely, low density polyethylene (LDPE)and ethyl vinyl acetate copolymer were successfully surface modifiedusing synthesized BP1. FIGS. 4.3 and 4.4 also confirms the presence ofcoating on the given polymers.

The above chemistry provides a simple and facile way to graft terminalvinyl functionality onto different polymer surfaces and backbones withC—H functionality. The available vinyl groups on the surface can be usedfor further chemical modifications, cross-linking reactions, and otherpolymerization techniques.

It should be noted that ratios, concentrations, amounts, and othernumerical data may be expressed herein in a range format. It is to beunderstood that such a range format is used for convenience and brevity,and thus, should be interpreted in a flexible manner to include not onlythe numerical values explicitly recited as the limits of the range, butalso to include all the individual numerical values or sub-rangesencompassed within that range as if each numerical value and sub-rangeis explicitly recited. To illustrate, a concentration range of “about0.1% to about 5%” should be interpreted to include not only theexplicitly recited concentration of about 0.1 wt % to about 5 wt %, butalso include individual concentrations (e.g., 1%, 2%, 3%, and 4%) andthe sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within theindicated range. In an embodiment, the term “about” can includetraditional rounding according to significant figures of the numericalvalue. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ toabout ‘y’”.

Many variations and modifications may be made to the above-describedembodiments. All such modifications and variations are intended to beincluded herein within the scope of this disclosure and protected by thefollowing claims.

Therefore, at least the following is claimed:
 1. A structure,comprising: a surface having a polymer, wherein the polymer comprises alinear or branched polyethylenimine polymer that has been quaternizedwith a hydrophobic side chain moiety (R1) and a photo cross-linkablemoiety (B), wherein the polymer is covalently attached to the surfacethrough the photo cross-linkable moiety, and wherein the structure hasan antimicrobial characteristic, wherein the linear or branchedpolyethylenimine polymer has the following structure:

wherein R1 is a hydrocarbon chain including a C═C group in the chain,wherein R2 is a hydrocarbon carbon chain linking moiety, saturated orunsaturated, wherein the structure is selected from the group consistingof: a fabric, a textile article, a natural fiber, a synthetic fiber, aporous membrane, a plastic structure, a oxide structure having afunctionalized layer on the surface of the structure, a metal structurehaving a functionalized layer on the surface of the structure, a glassstructure having a functionalized layer on the surface of the structure,and a combination thereof.
 2. The structure of claim 1, wherein theantimicrobial characteristic causes a substantial amount ofmicroorganisms to be killed.
 3. The structure of claim 1, wherein themicroorganism is selected from the group consisting of: gram positivebacteria, gram negative bacteria, protozoan, fungi, and algae.
 4. Thestructure of claim 1, wherein the antimicrobial characteristic causes amicroorganism growth to be inhibited or substantially inhibited.
 5. Thestructure of claim 1, wherein the microorganism is bacterium, andwherein the bacterium is selected from the group consisting of: grampositive bacteria, and gram negative bacteria.
 6. The structure of claim1, wherein the functionalized layer can have a thickness of about 2nanometers (nm) to 1 micrometer (μm).
 7. The structure of claim 1,wherein the antimicrobial characteristic of the surface is characterizedin that it kills greater than about 90% of the microorganisms on thesurface.
 8. The structure of claim 1, wherein the antimicrobialcharacteristic of the surface is characterized in that it kills greaterthan about 99% of the microorganisms on the surface.
 9. The structure ofclaim 1, wherein the C═C group of R1 is at the terminal end of R1. 10.The structure of claim 1, wherein the structure is selected from thegroup consisting of: a fabric, a textile article, a natural fiber, asynthetic fiber, and a combination thereof.
 11. The structure of claim10, wherein the functionalized layer can have a thickness of about 2nanometers (nm) to 1 micrometer (μm).
 12. The structure of claim 11,wherein the antimicrobial characteristic of the surface is characterizedin that it kills greater than about 90% of the microorganisms on thesurface.
 13. The structure of claim 11, wherein the antimicrobialcharacteristic of the surface is characterized in that it kills greaterthan about 99% of the microorganisms on the surface.
 14. The structureof claim 1, wherein the structure is a oxide structure having afunctionalized layer on the surface of the structure, a metal structurehaving a functionalized layer on the surface of the structure, a glassstructure having a functionalized layer on the surface of the structure,and a combination thereof.
 15. The structure of claim 14, wherein thefunctionalized layer can have a thickness of about 2 nanometers (nm) to1 micrometer (μm).
 16. The structure of claim 15, wherein theantimicrobial characteristic of the surface is characterized in that itkills greater than about 90% of the microorganisms on the surface. 17.The structure of claim 15, wherein the antimicrobial characteristic ofthe surface is characterized in that it kills greater than about 99% ofthe microorganisms on the surface.